The present invention relates to a device for co-operating with a machine condition analysis apparatus, and to a method of operating such a device. The invention also relates to a kit of parts comprising such a device, and to a system for evaluating the condition of a machine.
Machines with moving parts are subject to wear with the passage of time, which often causes the condition of the machine to deteriorate. Examples of such machines with movable parts are motors, pumps, generators, compressors, lathes and CNC-machines. It is known to, more or less regularly, investigate the operating condition of such machines. The operating condition can be determined by measuring the amplitude of vibrations in a bearing and by measuring temperature changes on the casing of the machine, which temperatures are dependent on the operating condition of the bearing. Such condition checks of machines with rotating or other moving parts are of great significance for safety and also for the length of the life of such machines. It is known to perform such measurements on machines completely manually. This ordinarily is done by an operator with the help of a measuring instrument performing measurements at a number of measuring points on a machine. The measuring data obtained by means of the measuring instrument for each measuring point is noted down on a pre-printed form. For a machine it can be necessary to have a number of measuring points in order to later be able to determine the overall operating condition of the machine. For example, three measuring points are often used for the measurement of vibrations of a motor, in such a way that the vibrations are measured in three mutually perpendicular directions, i.e. in the X-direction, in the Y-direction and in the Z-direction. The operator must note down each measured value on the form. It is furthermore necessary for the operator to evaluate the measured values so that he can make a judgement on whether the measured amplitude measurement values indicate a change for a measuring position so that the machine can be serviced if the measured values indicate wear. This places a large demand on the professional knowledge of the service personnel of which vibration and temperature measurement values are acceptable and which measurement values are not acceptable.
In order to identify damage to bearings it is known to use a shock impulse measur-ing apparatus by means of which damage to bearings can be determined in machines with rotating machine parts. In order to perform such measurements at a measuring point, the diameter of the shaft and the rotational speed of the shaft are set on a measuring scale. These values, which are set by hand, function as a reference level. If the measured values measured by means of the measuring instrument are greater than the reference level, this can be indicated by means of a warning lamp or by means of a sound signal.
It is known from EP-0 194 333 to provide each measuring point with identity data which is automatically readable by means of a separate reading probe. EP-0 194 333 also describes that the characteristic data values for the measuring point are readable at the measuring point so that the above described reference value can be generated automatically. The reference value is consequently calculated in a standardized and unambiguous way from the characteristic data values. Consequently, according to this known technique, the one and the same reference value is valid for all bearings with a certain shaft diameter and a certain rotational speed.
EP-0 211 212 describes a measuring instrument for detecting and evaluating data representative of the condition of a machine. The described measuring instrument has a measuring probe which is combined with a sensor probe for reading a measuring point code, whereby the measuring probe and the code, sensing probe are provided in a common mobile casing.
The problem to be solved by the present invention is to enable an increased accuracy in detecting changes of the condition of a machine.
This problem is solved according to the invention by a method of operating a device which is firmly mounted on or at a measuring point on a machine with a movable part. The device has a connection coupling to which a sensor unit is removably attachable for coupling machine vibrations to said sensor unit; an information carrier comprising a writable and readable memory means; and a communications means for co-operating with the information carrier and for communicating with an analysis apparatus. The method comprises the steps of:
a) attaching a sensor unit to said connection coupling for producing a first condition value by performing a measurement; said first condition value being dependent on the actual condition of the machine;
b) receiving said first condition value via said communications means; and
c) storing said first condition value in said writable and readable memory means.
The first condition value can subsequently be used as a reference condition value. With the object of providing a determination of whether some measurable condition change is present, a method according to an embodiment of the invention comprises the steps of:
a) attaching a sensor unit to said connection coupling for producing a second actual condition value at a time point later than the time of production of said first condition value, said second actual condition value being dependent on the actual condition at the measuring point;
b) delivering said first condition value from the information carrier, via said communications means so that the first condition value can be used as a reference condition value, whereby possible condition changes can be determined by comparing said second actual condition value with said first reference condition value.
An embodiment of the invention relates to a device for co-operating with a machine condition analysis apparatus, the device being adapted to be firmly mounted on or at a measuring point on a machine. The device comprises a connection coupling to which a sensor unit is removably attachable for coupling machine vibrations to said sensor unit; an information carrier comprising a writable memory means so that storing of a local reference condition value is made possible; and
a) a communications means for co-operating with the information carrier and for communicating with the analysis apparatus.
A condition analysing system, comprises:
a) a movable analysis apparatus and a sensor unit for producing a condition value by means of measuring at a measuring point on a machine, said condition value being dependent on movement and indicative of the actual condition of the machine; and
b) a device comprising an information carrier which is placed on, or in the vicinity of, a measuring point on a machine. The analysis apparatus is arranged to store the condition value in the information carrier, which is writable, so that the condition value subsequently can be used as a reference condition value.
According to an embodiment of the system, the device comprises:
a) interpretation information, stored on the information carrier, which defines technical type values for the machine and/or the movable part in such a way that the actual condition value is able to be generated dependent on an actual measured value when the measured value is interpreted in combination with the interpretation information. The device also comprises a communication means for co-operating with the information carrier and for communicating with the analysis apparatus. The device may also comprise:
b) a communication means for co-operating with the analysis apparatus, which, dependent on an activating signal, reads interpretation information from the information carrier and delivers this information to the analysis apparatus; wherein the communication means, dependent on the activation signal, reads the reference condition value from the information carrier and delivers this to the analysis apparatus thereby enabling the generation of a relation value indicating a changed condition.
The communication means comprises a transceiver for communicating with the analysis apparatus by means of radio communication or optical transmitters and optical receivers. The communication means also comprises contact means for ohmic contact between the information carrier and the analysis apparatus.